Method for measuring biaxial stress in a body subjected to stress inducing loads

Claim 1

In a method for ultrasonically measuring stress in a test article, the steps comprising: A. obtaining a transit time differential between the second wave echo for a longitudinal wave propagated along a first path through a stressed test article and the first wave echo for at least one shear wave propagated through the article along a second path paralleling said first path; and B. comparing the obtained transit time differential to an established transit time differential indicative of a measurement of stress.

Claim 10

A method for determining the magnitude of biaxial stress in metallic test articles, comprising the steps of: A. serially subjecting a specimen having characteristics similar to the characteristics of an article to be tested to a series of incrementally increased stress loads of known magnitudes, electronically establishing a transit time indication for the second wave echo for a longitudinal wave propagated through the specimen along a given path as the specimen is subjected to each load of the series for thus obtaining a first series of first transit time indications; B. electronically establishing a transit time indication for the first wave echo for each of a pair of orthogonally related shear waves propagated along paths paralleling said given path through said specimen for vibrating particles of the crystalline lattice thereof in the planes of a first and a second orthogonally related stress axis extended through the specimen as the specimen is subjected to each stress load of the series of known stress loads for thus obtaining a second and a third series of transit time indications; C. comparing the indications of said first series of transit time indications with the indications of said second and third transit time indications for obtaining a first and a second series of transit time differentials, and dividing each of the transit time differentials by the total length of the paths through the specimen, for thus establishing a series of time differential values indicative of stress magnitude for the orthogonally related stress axes for said specimen; D. obtaining a pair of transit time differential indications between the second wave echo for a longitudinal wave propagated along a first path through a test article subjected to an unknown stress and the first wave echo for each shear wave of a pair of shear waves propagated along a second path extended through the test article paralleling said first path for vibrating the crystalline lattice thereof in the planes of a first and a second stress axis for said test specimen; and E. comparing said pair of transit time differential values obtained for the test article to the series of time differential values established for the specimen for thus determining the magnitude of stress occurring along the first and second stress axes of the test article.

Claim 11

A method for determining the magnitude of biaxial stress in metallic test articles, comprising the steps of: A. serially subjecting a specimen having characteristics similar to the characteristics of an article to be tested to a series of incrementally increased stress loads of known magnitudes, electronically establishing a transit time indication for the second wave echo for a longitudinal wave propagated through the specimen along a given path as the specimen is subjected to each load of the series for thus obtaining a first series of first transit time indications; B. electronically establishing a transit time indication for the first wave echo for each of a pair of orthogonally related shear waves propagated along paths paralleling said given path through said specimen for vibrating particles of the crystalline lattice thereof in the planes of a first and a second orthogonally related stress axis extended through the specimen as the specimen is subjected to each stress load of the series of known stress loads for thus obtaining a second and a third series of transit time indications; C. comparing the indications of said first series of transit time indications with the indications of said second and third transit time indications for obtaining a first and a second series of transit time differentials, and dividing each of the transit time differentials by the total length of the paths through the specimen, for thus establishing a series of time differential values indicative of stress magnitude for the orthogonally related stress axes for said specimen; D. obtaining a pair of transit time differential indications between the second wave echo for a longitudinal wave propagated along a first path through a test article subjected to an unknown stress and the first wave echo for each shear wave of a pair of shear waves propagated along a second path extended through the test article paralleling said first path for vibrating the crystalline lattice thereof in the planes of a first and a second stress axis for said test specimen; and E. comparing said pair of transit time differential values obtained for the test article to the series of time differential values established for the specimen for thus determining the magnitude of stress occurring along the first and second stress axes of the test article.